Here's some code that IntelliJ recommended I used ...

# announcements

[redrield]

Here's some code that IntelliJ recommended I used Sequence with (hence the asSequence and toList)

task.command.requiredSubsystems.asSequence().filter { msg.shouldStartDefault(it) }
                    .mapNotNull(Subsystem::defaultCommand).toList()
                    .forEach {
                        handle(Message.Start(it))
                    }

[gildor]

toList is redundant in this case.
If Kotlin plugin convert it like that you should report an issue, because forEach available for sequences, no need to convert to list